JP7625993B2 - Optical fiber and method for manufacturing optical fiber - Google Patents

Description

This disclosure relates to optical fibers and methods for manufacturing optical fibers.

Optical fibers in which the outer circumference of a glass fiber is covered with a resin coating layer are known (for example, Patent Document 1).

JP 2003-292334 A

The purpose of this disclosure is to prevent optical fiber breakage.

According to one aspect of the present disclosure,
Glass fiber;
a resin coating layer covering the outer periphery of the glass fiber;
having
At a plurality of measurement points set at a predetermined interval in the axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis based on the outer periphery of the resin coating layer is measured, and in a spectrum obtained by Fourier transforming a waveform showing the amount of eccentricity for each position of the plurality of measurement points, the maximum value of the amplitude of the amount of eccentricity is 6 μm or less, and the wavelength at which the amplitude of the amount of eccentricity is maximum is 0.1 m or more.
An optical fiber is provided.

According to yet another aspect of the present disclosure,
forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
The present invention provides a method for manufacturing an optical fiber, in which the circumference of the largest roller among all rollers, including a roller located immediately below the curing device and a plurality of guide rollers downstream of the roller, is 0.2 m or more.

According to yet another aspect of the present disclosure,
forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
A method for manufacturing an optical fiber is provided in which vibration of the optical fiber is suppressed using a vibration suppressing section installed downstream of the curing device and upstream of a roller located immediately below the curing device.

According to yet another aspect of the present disclosure,
forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
There is provided a method for manufacturing an optical fiber, in which a roller located immediately below the curing device is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber.

This disclosure makes it possible to prevent optical fiber breakage.

FIG. 1 is a schematic cross-sectional view illustrating an optical fiber according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view for explaining the definition of the eccentricity of a glass fiber. FIG. 3 is a diagram of an eccentricity waveform showing the eccentricity of the glass fiber with respect to the axial position of the glass fiber. FIG. 4 is a diagram showing an example of a spectrum obtained by Fourier transforming the eccentricity waveform. FIG. 5 is a schematic diagram illustrating an optical fiber manufacturing apparatus according to an embodiment of the present disclosure.

[Description of the embodiments of the present disclosure]
<Findings gained by the inventors>
First, the findings of the inventors will be described.

In recent years, there has been a demand for optical fibers with a smaller outer diameter in order to package multiple optical fibers at high density in optical cables. Specifically, the outer diameter of some optical fibers in recent years is 200 μm or less.

In the manufacturing process for optical fibers with such small diameters, the optical fiber is more susceptible to breakage than optical fibers with conventional outer diameters. If the optical fiber breaks during the manufacturing process, there is a risk that the manufacturing efficiency of the optical fiber will decrease. For this reason, there was a demand for unprecedented innovations in the manufacturing process.

After extensive research into the above-mentioned issues, the inventors discovered that the frequency of optical fiber breakage during the manufacturing process depends on the eccentricity of the glass fiber in the optical fiber.

If the glass fiber vibrates in the radial direction as it passes through the die in the resin coating device, the glass fiber becomes eccentric with respect to the opening of the die, and the resin coating layer is formed in this state. This causes the resin coating layer to become thinner in the direction in which the central axis of the glass fiber is shifted from the central axis of the optical fiber. In this case, when the optical fiber comes into contact with burrs on the guide roller or foreign matter on the guide roller, a large stress may be locally applied to the glass fiber through the part where the resin coating layer is thin. This can cause damage such as cracks in the glass fiber. As a result, the optical fiber may break due to damage to the glass fiber.

Therefore, in order to study the eccentricity of the above-mentioned glass fiber, the inventors performed a Fourier transform on the waveform showing the eccentricity of the glass fiber relative to the axial position of the glass fiber, and analyzed the spectrum obtained by the Fourier transform. As a result, they found out what components (elements) in the spectrum affect the breakage of the optical fiber.

As a result, the inventors have succeeded in suppressing breakage of optical fiber by adjusting the components that affect breakage of optical fiber in the spectrum obtained by Fourier transform of the eccentricity waveform of glass fiber.

This disclosure is based on the above findings made by the present inventors.

<Embodiments of the present disclosure>
Next, embodiments of the present disclosure will be listed and described.

[1] An optical fiber according to one embodiment of the present disclosure,
Glass fiber;
a resin coating layer covering the outer periphery of the glass fiber;
having
At a plurality of measurement points set at predetermined intervals in the axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis based on the outer periphery of the resin coating layer is measured, and in a spectrum obtained by Fourier transforming a waveform showing the amount of eccentricity for each position of the plurality of measurement points, the maximum value of the amplitude of the amount of eccentricity is 6 μm or less, and the wavelength at which the amplitude of the amount of eccentricity is maximum is 0.1 m or more .
According to this configuration, breakage of the optical fiber can be suppressed.

[4] A method for producing an optical fiber according to still another aspect of the present disclosure includes the steps of:
forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
Among all rollers including a direct below roller located directly below the curing device and a plurality of guide rollers downstream of the direct below roller, the circumference of the largest roller is set to 0.2 m or more.
According to this configuration, breakage of the optical fiber can be suppressed.

[5] A method for producing an optical fiber according to still another aspect of the present disclosure includes the steps of:
forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
The vibration of the optical fiber is suppressed using a vibration suppressing section installed downstream of the curing device and upstream of a roller located immediately below the curing device.
According to this configuration, breakage of the optical fiber can be suppressed.

[6] A method for producing an optical fiber according to still another aspect of the present disclosure includes the steps of:
forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
A roller located immediately below the curing device is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber.
According to this configuration, breakage of the optical fiber can be suppressed.

[7] In the method for producing an optical fiber according to any one of the above [4],
In the step of transporting the optical fiber,
A vibration suppressing section disposed downstream of the curing device and upstream of the direct below roller is used to suppress vibration of the optical fiber.
According to this configuration, breakage of the optical fiber can be stably suppressed.

[8] In the method for producing an optical fiber according to any one of the above [4],
In the step of transporting the optical fiber,
The immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber.
According to this configuration, breakage of the optical fiber can be stably suppressed.

[9] In the method for producing an optical fiber according to any one of the above [5],
In the step of transporting the optical fiber,
The immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber.
According to this configuration, breakage of the optical fiber can be stably suppressed.

[10] In the method for producing an optical fiber according to any one of the above [4],
In the step of transporting the optical fiber,
a vibration suppressing unit disposed downstream of the curing device and upstream of the direct below roller is used to suppress vibration of the optical fiber;
The immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber.
According to this configuration, breakage of the optical fiber can be stably suppressed.

[Details of the embodiment of the present disclosure]
Next, an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

<One embodiment of the present disclosure>
(1) Optical Fiber An optical fiber 10 according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the optical fiber according to the embodiment.

In the following, the "axial direction" of the glass fiber 100 refers to the direction along the central axis of the glass fiber 100, which can be rephrased as the longitudinal direction of the glass fiber 100. The "radial direction" of the glass fiber 100 refers to the direction perpendicular to the axial direction of the glass fiber 100, which can be rephrased as the transverse direction of the glass fiber 100 in some cases. The "circumferential direction" of the glass fiber 100 refers to the direction along the outer periphery of the glass fiber 100 (the circumferential direction in FIG. 1). The same terms as those for the glass fiber 100 can be used for the optical fiber 10.

As shown in FIG. 1, the optical fiber 10 of this embodiment is configured as a linear body in which the outer circumference of the glass fiber 100 is covered with a resin coating layer 200. That is, the optical fiber 10 has, for example, the glass fiber 100 and the resin coating layer 200 in this order from the central axis side of the glass fiber 100 to the outer circumference side.

The term "optical fiber 10" used here includes the optical fiber strand before it is colored and the optical fiber core wire after it is colored. In the following, for example, the optical fiber 10 will be described as an optical fiber strand.

[Glass fiber]
The glass fiber 100 is configured, for example, as an optical transmission body that transmits light introduced into the optical fiber 10 along the axial direction of the optical fiber 10. The glass fiber 100 is also called, for example, a "bare optical fiber." The glass fiber 100 has silica (SiO ₂ ) glass as a base material (main component) and has a core 120 and a cladding 140.

[Resin coating layer]
The resin coating layer 200 is provided, for example, so as to cover the outer periphery of the glass fiber 100 and is configured to protect the glass fiber 100 .

In this embodiment, the resin coating layer 200 has, for example, a first resin coating layer (primary resin coating layer) 220 and a second resin coating layer (secondary resin coating layer) 240.

The first resin coating layer 220 is provided, for example, to cover the outer periphery of the clad 140 of the glass fiber 100 and is in contact with the outer periphery of the clad 140. The second resin coating layer 240 is provided, for example, to cover the outer periphery of the first resin coating layer 220 and is in contact with the outer periphery of the first resin coating layer 220.

The first resin coating layer 220 and the second resin coating layer 240 are formed, for example, as a cured product obtained by curing an ultraviolet-curable resin composition by irradiating it with ultraviolet light. Examples of the base resin in the ultraviolet-curable resin composition include urethane acrylate.

In this embodiment, the optical fiber 10 is configured to have a smaller diameter than in the past. Specifically, the outer diameter of the resin coating layer 200 described above (i.e., the outer diameter of the second resin coating layer 240) is, for example, 190 μm or less. This allows multiple optical fibers 10 to be densely packed into an optical cable.

(2) Amount of eccentricity of glass fiber Next, the amount of eccentricity of the glass fiber 100 in this embodiment will be described with reference to Fig. 2 to Fig. 4. Fig. 2 is a schematic cross-sectional view for explaining the definition of the amount of eccentricity of a glass fiber. Fig. 3 is a diagram of an eccentricity waveform showing the amount of eccentricity of the glass fiber with respect to the axial position of the glass fiber. Fig. 4 is a diagram showing an example of a spectrum obtained by Fourier transforming the eccentricity waveform.

First, the definition of the eccentricity of a glass fiber will be explained with reference to FIG. 2. Note that FIG. 2 is merely an explanatory diagram and does not show the state of the optical fiber 10 of this embodiment. However, to simplify the explanation, the same reference numerals as in FIG. 1 are used.

As shown in FIG. 2, the eccentricity d of the glass fiber 100 is defined as the distance (radial deviation, radial displacement) from the central axis RC based on the outer periphery of the resin coating layer 200 to the central axis GC of the glass fiber 100.

Here, the eccentricity of the glass fiber 100 is measured, for example, by an eccentricity fluctuation observation device.

The eccentricity variation observation device is configured as an eccentricity image recognition device, and has, for example, a first light source, a first imaging unit, a second light source, and a second imaging unit.

The first light source is arranged to irradiate light in the short direction of the optical fiber 10 to be measured. The light of the first light source includes a wavelength that transmits through the resin coating layer 200. The first imaging unit is arranged to face the first light source across the optical fiber 10 to be measured, and is configured to obtain an image of the light that has passed through the optical fiber 10. The second light source and the second imaging unit are configured in the same way, except that they are arranged perpendicular to the facing direction of the first light source and the first imaging unit.

With this configuration, the outer periphery position of the resin coating layer 200 and the inner periphery position of the resin coating layer 200 (the outer periphery position of the glass fiber 100) can be determined based on the light transmitted through the optical fiber 10 in two axial directions that are perpendicular to the central axis of the optical fiber 10 and perpendicular to each other, and the eccentricity of the glass fiber 100, which is the distance between their centers, can be measured. In other words, the eccentricity of the glass fiber 100 can be measured without destroying the optical fiber 10.

By measuring the eccentricity of the glass fiber 100 at multiple measurement points set at a predetermined interval in the axial direction of the glass fiber 100, the positions of the multiple measurement points are plotted on the horizontal axis and the eccentricity at each position is plotted on the vertical axis, thereby obtaining a waveform (distribution) of the eccentricity. Hereinafter, the waveform of the eccentricity of the glass fiber 100 is also referred to as the "eccentricity waveform."

The above measurement produces an eccentricity waveform, such as that shown in Figure 3. Note that the "eccentricity" on the vertical axis of Figure 3 is the absolute value of the eccentricity, regardless of direction, or in other words, corresponds to the radius r in the polar coordinate system.

As shown in FIG. 3, the eccentricity waveform in the actual optical fiber 10 is not a neat sine wave, but has a complex shape due to the vibration amount, vibration direction, and vibration frequency in each part of the optical fiber manufacturing device 50, which will be described later.

Therefore, the inventors performed a Fourier transform on the eccentricity waveform of the optical fiber 10, as shown in Figure 4, and analyzed the spectrum obtained by the Fourier transform.

As a result, the inventors discovered that in the spectrum obtained by Fourier transforming the eccentricity waveform, the "maximum value of the eccentricity amplitude" or the "wavelength at which the eccentricity amplitude is maximum" affects breakage of the optical fiber 10. The component at which the eccentricity amplitude is maximum is also called the "maximum amplitude component."

Based on the above findings, it is preferable that the optical fiber 10 of this embodiment satisfies at least one of the following requirements regarding the eccentricity of the glass fiber 100:

As shown in FIG. 4, in this embodiment, in the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the maximum value of the eccentricity amplitude (the amplitude value of the maximum amplitude component) is, for example, 6 μm or less.

If the maximum value of the amplitude of the eccentricity exceeds 6 μm, the glass fiber 100 will be locally largely eccentric at the position where the eccentricity components with different wavelengths overlap. This makes it easy for the resin coating layer to become locally thin. As a result, there is a risk of the glass fiber 100 breaking more frequently. In contrast, in this embodiment, by setting the maximum value of the amplitude of the eccentricity to 6 μm or less, it is possible to suppress locally large eccentricity of the glass fiber 100 even if the eccentricity components with different wavelengths overlap. This makes it possible to suppress the resin coating layer from becoming locally thin. As a result, it is possible to reduce the frequency of breakage of the glass fiber 100.

The maximum amplitude of the eccentricity is not particularly limited, but it is preferable that it is as close to 0 μm as possible.

In addition, as shown in FIG. 4, in this embodiment, in the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the wavelength at which the amplitude of the eccentricity is maximum (the wavelength of the maximum amplitude component) is, for example, 0.1 m or more.

If the wavelength at which the amplitude of the eccentricity is maximum is less than 0.1 m, there is a lot of overlapping of other components having different wavelengths from the component at which the amplitude of the eccentricity is maximum. For this reason, the resin coating layer is often locally thin. In other words, the number of places where the resin coating layer is thin per unit length in the axial direction of the glass fiber 100 increases. As a result, there is a risk of the frequency of breakage of the glass fiber 100 increasing. In contrast, in this embodiment, by setting the wavelength at which the amplitude of the eccentricity is maximum to 0.1 m or more, it is possible to reduce the number of "other components having different wavelengths" that overlap with the component at which the amplitude of the eccentricity is maximum. This makes it possible to suppress the resin coating layer from becoming locally thin, that is, to suppress the increase in the number of places where the resin coating layer is thin per unit length in the axial direction of the glass fiber 100. As a result, it is possible to reduce the frequency of breakage of the glass fiber 100.

The upper limit of the wavelength at which the amplitude of the eccentricity is maximum is not particularly limited, and is preferably as large as possible. However, taking into consideration the line speed of the optical fiber manufacturing device 50 described below, the wavelength at which the amplitude of the eccentricity is maximum is, for example, 1 m or less.

(3) Optical Fiber Manufacturing Apparatus Next, an optical fiber manufacturing apparatus 50 according to this embodiment will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram showing the configuration of the optical fiber manufacturing apparatus according to this embodiment.

As shown in FIG. 5, the optical fiber manufacturing apparatus 50 of this embodiment includes, for example, a drawing furnace 510, a fiber position measuring unit 522, a cooling device 523, an outer diameter measuring unit 524, a resin coating device 530, a curing device 540, a conveying unit 550, a bobbin 560, and a control unit 590. The equipment components other than the control unit 590 are provided in this order.

Hereinafter, for each device component of the optical fiber manufacturing apparatus 50, the side closer to the gripping mechanism 512 will be referred to as "upstream" and the side closer to the bobbin 560 will be referred to as "downstream."

The drawing furnace 510 is configured to form the glass fiber 100. The glass base material G is heated in the drawing furnace 510, and the softened glass is drawn out to form the glass fiber 100 having a small diameter.

The fiber position measurement unit 522 is configured to measure the horizontal position of the glass fiber 100.

The cooling device 523 is configured to cool the glass fiber 100 formed in the drawing furnace 510.

The outer diameter measuring unit 524 is configured to measure the outer diameter of the glass fiber 100 before it is resin-coated.

The resin coating device 530 is configured to form a resin coating layer 200 so as to cover the outer periphery of the glass fiber 100. The resin coating layer 200 has a die that applies an ultraviolet-curable resin composition to the outer periphery of the glass fiber 100 while inserting the glass fiber 100.

In this embodiment, the resin coating device 530 has two dies that form the first resin coating layer 220 and the second resin coating layer 240 in this order from the central axis side to the outer periphery side of the glass fiber 100.

The curing device 540 is configured to irradiate the resin coating layer 200 with ultraviolet light to cure the resin coating layer 200.

The conveying section 550 is configured to convey, for example, the optical fiber 10 with the resin coating layer 200 cured. Specifically, the conveying section 550 has, for example, a plurality of guide rollers 552, 556 and a capstan 554. The direct below roller 552a, which is one of the plurality of guide rollers 552, is located, for example, directly below the curing device 540. The capstan 554 is, for example, provided downstream of the direct below roller 552a and configured to convey (pull) the optical fiber 10 with a predetermined tension while gripping the optical fiber 10 between the belt and the roller. The screening rollers 552c, 552d and 552e of the plurality of guide rollers 552 are provided downstream of the capstan 554 and configured to apply a screening tension to the optical fiber 10 together with the capstan 554. The guide roller 556 is provided downstream of the screening roller 552e and configured to adjust the tension of the optical fiber 10 by moving up and down in response to fluctuations in the tension of the optical fiber 10.

The bobbin 560 is provided, for example, downstream of the guide roller 556 and is configured to wind up the optical fiber 10.

The control unit 590 is, for example, connected to each part of the optical fiber manufacturing apparatus 50 and configured to control them. The control unit 590 is, for example, configured as a computer.

In this embodiment, in order to manufacture an optical fiber 10 that satisfies the requirements for the eccentricity of the glass fiber 100 described above, the optical fiber manufacturing device 50 is configured, for example, as follows.

In this embodiment, the circumference of the largest roller among all rollers, including the immediately below roller 552a and the multiple guide rollers 552 downstream of the immediately below roller 552a, is, for example, 0.2 m or more.

It is preferable that the circumference of the largest guide roller 552 is, for example, 0.9 m or less.

In addition, in this embodiment, as shown in FIG. 5, the conveying section 550 has, for example, a vibration suppression section 555. The vibration suppression section 555 is installed, for example, downstream of the curing device 540 and upstream of the direct below roller 552a located directly below the curing device 540. The vibration suppression section 555 is configured, for example, such that two rollers contact the optical fiber from different directions to suppress vibration of the optical fiber 10.

The vibration suppression section 555 suppresses the vibration of the optical fiber 10, thereby stably maintaining the position of the central axis of the glass fiber 100. In other words, the eccentricity of the glass fiber 100 can be suppressed.

In addition, in this embodiment, as shown in FIG. 5, the directly below roller 552a located directly below the curing device 540 is fixed independently from, for example, other equipment components related to the manufacture of the optical fiber 10. Specifically, the directly below roller 552a is fixed to the floor, for example, without being connected to other equipment components.

By using the direct-below roller 552a in a fixed state independent of other equipment components involved in the manufacture of the optical fiber 10, it is possible to suppress the direct-below roller 552a from being subjected to vibrations from other equipment components. As a result, in the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the maximum value of the amplitude of the eccentricity can be reduced, and the wavelength at which the amplitude of the eccentricity is maximum can be lengthened.

<Other embodiments of the present disclosure>
Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

In the above embodiment, the optical fiber 10 is illustrated and described as an optical fiber strand before being colored, but as described above, the optical fiber 10 may be an optical fiber core wire after being colored. In other words, the optical fiber 10 may have a colored layer that covers the outer periphery of the resin coating layer 200.

In the above embodiment, the resin coating layer 200 is described as being composed of two layers, but this is not limited to this case. The resin coating layer 200 may be composed of only one layer, or may be composed of three or more layers.

In the above embodiment, the optical fiber 10 satisfies both of the following requirements (i) and (ii) regarding the eccentricity of the glass fiber 100. However, the present invention is not limited to this case.
(i) In the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the maximum value of the amplitude of the eccentricity is 6 μm or less.
(ii) In a spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the wavelength at which the amplitude of the eccentricity is maximum is 0.1 m or more.
If the optical fiber 10 satisfies at least one of the requirements (i) and (ii), it is possible to obtain a significant effect of reducing the frequency of breakage of the glass fiber 100. However, the above-mentioned effect can be obtained more stably if both the requirements (i) and (ii) are satisfied.

In the above embodiment, a case has been described in which all of (x), (y), and (z) are implemented in order to manufacture the optical fiber 10 that satisfies the above-mentioned requirements for the amount of eccentricity of the glass fiber 100, but this is not limited to the case.
(x) The circumference of the largest roller among all rollers including the immediately below roller 552a located immediately below the curing device 540 and the multiple guide rollers 552 downstream of the immediately below roller 552a is 0.2 m or more.
(y) Vibration of the optical fiber 10 is suppressed by a vibration suppressing unit 555 installed downstream of the curing device 540 and upstream of a direct below roller 552 a located directly below the curing device 540 .
(z) The roller 552 a located immediately below the curing device 540 is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber 10 .
By implementing at least one of (x), (y) and (z), the above-mentioned effects can be obtained to a certain extent. However, by implementing many of (x), (y) and (z), the above-mentioned effects can be obtained more stably.

Next, examples of the present disclosure will be described. These examples are merely examples of the present disclosure, and the present disclosure is not limited to these examples.

(1) Preparation of Optical Fibers Optical fibers of samples A1 to A4, B1 and B2 were prepared under the conditions shown in Table 1 below.

Common conditions not listed in Table 1 are as follows:
Outer diameter of glass fiber: 125 μm
Number of resin coating layers: 2 layers

(2) Evaluation [Eccentricity Measurement]
An eccentricity fluctuation observation device was used to measure the eccentricity of the glass fiber at a plurality of measurement points set at predetermined intervals in the axial direction of the glass fiber, thereby obtaining a waveform of the eccentricity for each of the positions of the plurality of measurement points.

The eccentricity waveform of the optical fiber was then Fourier transformed (FFT: Fast Fourier Transform) and the spectrum obtained by the Fourier transform was analyzed. In this way, the "maximum value of the eccentricity amplitude" and the "wavelength at which the eccentricity amplitude is maximum" were obtained from the spectrum obtained by Fourier transforming the eccentricity waveform. Note that the "wavelength at which the eccentricity amplitude is maximum" is referred to below as the "wavelength of the maximum amplitude component."

[Disconnection frequency measurement]
The optical fiber of each sample was rewound under a tension of 1.5 kg during the manufacturing process, and the number of breaks in the optical fiber was measured. For each sample, the break frequency was calculated as the number of breaks per 1000 kilometers (Mm). As a result, a break frequency of less than 5 times/Mm was evaluated as "good", and a break frequency of 5 times/Mm or more was evaluated as "poor".

(3) Results The results of the evaluation of each sample are explained using Table 1 below.

[Samples B1 and B2]
In the samples B1 and B2, the maximum amplitude of the eccentricity exceeded 6 μm in the spectrum obtained by Fourier transforming the eccentricity waveform, and the wavelength at which the amplitude of the eccentricity became maximum in the spectrum obtained by Fourier transforming the eccentricity waveform was less than 0.1 m.

As a result, in samples B1 and B2, the optical fiber was prone to breakage, with a breakage frequency of 5 times/mm or more. In addition, sample B1, which has a relatively small diameter, tended to have a higher breakage frequency than sample B2, which has a conventional outer diameter.

In samples B1 and B2, the circumference of the maximum guide roller was less than 0.2 m, so the optical fiber could not be transported stably by the maximum guide roller. In addition, in samples B1 and B2, a vibration suppression section was not provided, so the position of the central axis of the glass fiber shifted significantly or at short intervals when the resin coating layer was coated due to vibrations from the transport section. In addition, in samples B1 and B2, the immediate below roller was used in a state connected to other equipment components, so the vibration of the immediate below roller became large or short-period.

For these reasons, in samples B1 and B2, in the spectrum obtained by Fourier transforming the eccentricity waveform, the maximum amplitude of the eccentricity was large and the wavelength at which the amplitude of the eccentricity was maximum was short. As a result, it is believed that samples B1 and B2 experienced higher frequency of breakage. It is also believed that the thinner the diameter of the optical fiber, the more likely it was to break.

[Samples A1 to A4]
In contrast, in the samples A1 to A4, the maximum amplitude of the eccentricity was 6 μm or less in the spectrum obtained by Fourier transforming the eccentricity waveform, and the wavelength at which the amplitude of the eccentricity was maximum was 0.1 m or more in the spectrum obtained by Fourier transforming the eccentricity waveform.

As a result, the optical fiber of samples A1 to A4 was less susceptible to breakage, with the breakage frequency being less than 5 times/mm.

In samples A1 to A4, the circumference of the largest guide roller was set to 0.2 m or more, allowing the optical fiber to be transported stably by the largest guide roller.

In addition, in samples A1 and A2, the provision of a vibration suppression section enabled the position of the central axis of the glass fiber to be stably maintained when coating the resin coating layer due to vibrations from the conveying section.

In addition, in samples A1 to A3, the roller directly below was used in a fixed state independent of other equipment components, which made it possible to suppress the increase in vibration of the roller directly below and the shortening of its period.

As a result, in samples A1 to A4, it was possible to reduce the maximum value of the amplitude of the eccentricity in the spectrum obtained by Fourier transforming the eccentricity waveform, and to lengthen the wavelength at which the amplitude of the eccentricity is maximum. As a result, it was confirmed that samples A1 to A4 were able to reduce the frequency of wire breakage, even though they had a smaller diameter than sample B1.

10 Optical fiber 50 Optical fiber manufacturing apparatus 100 Glass fiber 120 Core 140 Cladding 200 Resin coating layer 220 First resin coating layer 240 Second resin coating layer 430 Hardening device 510 Drawing furnace 512 Holding mechanism 514 Furnace tube 516 Heating element 518 Gas supply unit 522 Fiber position measuring unit 523 Cooling device 524 Outer diameter measuring unit 530 Resin coating device 540 Hardening device 550 Conveying unit 552 Guide roller 552a Directly below roller 552b Guide rollers 552c, 552d, 552e Screening roller 554 Capstan 555 Vibration suppressing unit 556 Guide roller 560 Bobbin 590 Control unit

Claims (8)

Glass fiber;
a resin coating layer covering the outer periphery of the glass fiber;
having
At a plurality of measurement points set at a predetermined interval in the axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis based on the outer periphery of the resin coating layer is measured, and in a spectrum obtained by Fourier transforming a waveform showing the amount of eccentricity for each position of the plurality of measurement points, the maximum value of the amplitude of the amount of eccentricity is 6 μm or less, and the wavelength at which the amplitude of the amount of eccentricity is maximum is 0.1 m or more.
Optical fiber. forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
A method for manufacturing an optical fiber, wherein the circumference of the largest roller among all rollers, including a roller located immediately below the curing device and a plurality of guide rollers located downstream of the roller, is 0.2 m or more. forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
A method for manufacturing an optical fiber, comprising: using a vibration suppressing unit disposed downstream of the curing device and upstream of a roller located directly below the curing device to suppress vibration of the optical fiber. forming a glass fiber;
forming a resin coating layer so as to cover an outer periphery of the glass fiber;
curing the resin coating layer using a predetermined curing device;
conveying the optical fiber with the cured resin coating layer;
having
In the step of forming the resin coating layer,
The outer circumferential diameter of the resin coating layer is 190 μm or less,
In the step of transporting the optical fiber,
The optical fiber manufacturing method uses a roller located immediately below the curing device, the roller being fixed independently from other equipment components involved in the manufacturing of the optical fiber. In the step of transporting the optical fiber,
3. The method for producing an optical fiber according to claim 2 , further comprising the step of: suppressing vibration of the optical fiber using a vibration suppressing section disposed downstream of the curing device and upstream of the roller just below the optical fiber. In the step of transporting the optical fiber,
3. The method for producing an optical fiber according to claim 2 , wherein the immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber. In the step of transporting the optical fiber,
4. The method for producing an optical fiber according to claim 3 , wherein the immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber. In the step of transporting the optical fiber,
a vibration suppressing unit disposed downstream of the curing device and upstream of the direct below roller is used to suppress vibration of the optical fiber;
3. The method for producing an optical fiber according to claim 2 , wherein the immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber.

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